Hi All,
This might be more of a Jinja question, but I couldn’t find an answer to this.
Say I have an inventory value that stores the main NIC name and I want to lookup the IP address for it from a fact. How can this be done in the one line? Non working example:
debug: msg=“ip address is {{ ansible_{{ main_nic }}.ipv4.address }}”
GS
You can build variables dynamically through hostvars, which is a hash of all variables, host by host:
{{ hostvars[inventory_hostname][“ansible_” + main_nic].ipv4.address }}
inventory_hostname is the name of the current host in the host loop.
(Nesting templates in templates definitely will not work)
Perfect. That works. Again, thank you 
GS
Hi Michael,
I tried using the {{ hostvars[inventory_hostname] trick but that variable
space does not include variables defined in a role such as “myrole/vars/main.yaml.”
How can I programmatically reference variables defined within a role?
Thank you,
–Ed
I believe there was a ticket about hostvars not including all of the variables, which it should, that should now be resolved.
If you still see this in 1.6 let me know.
Sorry to drag up an old thread, but this was one of the closer conversations out of the ones I found for what I was seeing.
Looking through old tickets, it looks like there used to be an issue when accessing hostvars[inventory_hostname] that you would not get all the vars associated with the host, such as ones added from add_host call. I see this does work, however, if I debug just the hostvars itself (not hostvars[inventory_hostname]) I don’t get the same results.
The var does exist, and it can be used in plays, I mainly keep running into this as I am debugging and trying to see what vars exist for all hosts
Given a host file of:
[launched]
10.0.3.234 test_var=test
10.0.3.162 test_var=test
And a playbook of
- name: Playbook testing inventory var debugging
hosts: launched
user: root
gather_facts: yes
tasks:
- name: Output inventory var
debug: var=test_var
- name: Output inventory var from hostvars
debug: var=hostvars[inventory_hostname].test_var
- name: Output hostvars[inventory_hostname]
debug: var=hostvars[inventory_hostname]
- name: Output hostvars
debug: var=hostvars
The last debug for var=hostvars will not output the vars from the inventory file. The var exists, so this is kind of cosmetic, but it threw me off for a bit as I was working with add_host for dynamic EC2 provisioning and wasn’t seeing the vars I was expecting when doing debug hostvars to look at all the vars for all hosts.
(ansible)[ec2-user@ip-10-0-0-226 playbooks]$ ansible-playbook -i launched test_inventory_var_debug.yml
PLAY [Playbook testing inventory var debugging] *******************************
GATHERING FACTS ***************************************************************
ok: [10.0.3.162]
ok: [10.0.3.234]
TASK: [Output inventory var] **************************************************
ok: [10.0.3.234] => {
“test_var”: “test”
}
ok: [10.0.3.162] => {
“test_var”: “test”
}
TASK: [Output inventory var from hostvars] ************************************
ok: [10.0.3.234] => {
“hostvars[inventory_hostname].test_var”: “test”
}
ok: [10.0.3.162] => {
“hostvars[inventory_hostname].test_var”: “test”
}
TASK: [Output hostvars[inventory_hostname]] ***********************************
ok: [10.0.3.234] => {
“hostvars[inventory_hostname]”: {
“ansible_all_ipv4_addresses”: [
“10.0.3.234”
],
…
“ansible_virtualization_type”: “xen”,
“group_names”: [
“launched”
],
“inventory_hostname”: “10.0.3.234”,
“inventory_hostname_short”: “10”,
“module_setup”: true,
“test_var”: “test”
}
}
ok: [10.0.3.162] => {
“hostvars[inventory_hostname]”: {
“ansible_all_ipv4_addresses”: [
“10.0.3.162”
],
…
“ansible_virtualization_type”: “xen”,
“group_names”: [
“launched”
],
“inventory_hostname”: “10.0.3.162”,
“inventory_hostname_short”: “10”,
“module_setup”: true,
“test_var”: “test”
}
}
TASK: [Output hostvars] *******************************************************
ok: [10.0.3.234] => {
“hostvars”: {
“10.0.3.162”: {
“ansible_all_ipv4_addresses”: [
“10.0.3.162”
],
…
“ansible_virtualization_type”: “xen”,
“module_setup”: true
}
}
}
ok: [10.0.3.162] => {
“hostvars”: {
“10.0.3.162”: {
“ansible_all_ipv4_addresses”: [
“10.0.3.162”
],
…
“ansible_virtualization_type”: “xen”,
“module_setup”: true
}
}
}
PLAY RECAP ********************************************************************
10.0.3.162 : ok=5 changed=0 unreachable=0 failed=0
10.0.3.234 : ok=5 changed=0 unreachable=0 failed=0
Anyways, let me know if I misunderstand this or if there is a different var to be looking at for the inventory vars. I can open an issue ticket also.
Thanks!
Michael